Euryhaline teleost fish adapt rapidly to salinity change and reduce their rate of ion secretion on entry to fresh water. Killifish (Fundulus heteroclitus) transferred from full-strength sea water to fresh water showed large reductions in plasma [Na(+)] and osmolality at 6 h which were corrected by 24 h. To mimic this in vitro, a hypotonic shock of 20-70 mosmol kg(-)(1) was applied on the basolateral side of opercular epithelia. This hypotonic shock reversibly reduced the short-circuit current… CONTINUE READING